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Nano Flex 3G Arm Warmer

3.5 out of 5 stars
2 Reviews
Color:Belgian Blue


Size Chart


Nano Flex 3G Arm Warmer

Rain or shine, wet or dry, these warmers give you the extra bit of warmth you need to stay comfortable when you're riding on a brisk day in early fall or late spring. The stretchy, fleece-backed thermal fabric is coated with millions of tiny nanofilaments that encourage water to bead up and roll off the garment, keeping light rain and tire spray at bay. That being said, the material is also highly breathable, making them a great option for dry days, too.


  • Arm warmers that work well for both wet and dry conditions
  • Water-repellent thermal fabric helps you stay warm and dry
  • Breathable construction prevents clamminess and overheating
  • Single, flat-lock seam ensures maximum comfort
  • Double-sided silicone gripper keeps the warmers in place
  • Easy to take off and stow in a jersey pocket if things warm up
  • Recommended for temperatures ranging from 54 - 68-degrees Fahrenheit
  • Item #CST00UJ
Nano Flex 3G
Claimed Weight
[pair] 2.3oz (78g)
Manufacturer Warranty
1 year

Overall Rating

3.5 based on 2 ratings

Review Summary

1 Stars - 0 reviews
2 Stars - 1 reviews
3 Stars - 0 reviews
4 Stars - 0 reviews
5 Stars - 1 reviews

Fits Small

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Runs smallTrue to sizeRuns large

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2 out of 5 stars

May 4, 2022

They changed the design unfortunately

I've used it several times

This used to be one of my favorite pieces of kit and I've been rocking these since the first iteration. Unfortunately they changed the design and removed the elastic band at the wide part of the arm warmer. So now they slide down when I'm riding. A flaw in nearly every arm warmer for tall, lanky dudes like myself. Such a shame. These used to be the only arm warmer that actually fit me, and didn't fall down.

Joshua T

Originally reviewed on

5 out of 5 stars

October 9, 2020

Excellent Warmers

I've used it several times
Size Bought:
5' 10"

They feel premium and do a great job at keeping my arms warm. As always with Castelli be sure to size up. Worth every penny

Ellery F